TSH-receptor antibody (TSH-R Ab) variations in patients undergoing subtotal thyroidectomy for Graves' disease: a prospective study.

Variations in circulating TSH-R Ab were correlated to the thyroid function outcome in a group of 43 patients who received subtotal thyroidectomy for Graves' disease. There were 36 females and 7 males, ranging in age from 18 to 63 years (mean +/- SD = 41.3 +/- 9.5 years). All patients were operated on by the same surgeon, with the same surgical technique, leaving a remnant of 4-5 grams of thyroid. When a condition of subclinical hypothyroidism was found after surgery, thyroid function was tested again within 2-3 months. Thus, in cases with persisting elevated TSH levels, L-thyroxine was administered. During follow-up a progressive decrease in the prevalence of euthyroid patients was documented (51.2% at 3 months, 30.2% at 2 years, 28% at 4 years), with a parallel increase in cases of subclinical and overt hypothyroidism. Two patients with persisting detectable TSH-R Abs showed recurrent disease within 2 years after surgery. No case of relapse was observed among patients who became TSH-R Ab negative. TSH-R Abs remained detectable in 68% of euthyroid and in 63.6% of subclinical hypothyroid patients before L-thyroxine administration, whereas TSH-R Abs remained positive in only 30% of patients with overt hypothyroidism, and became undetectable in most patients with subclinical hypothyroidism after L-thyroxine was begun. The persistence of TSH-R Abs in patients who have undergone surgery for Graves' disease should be considered a risk condition for relapse. These patients must be carefully followed-up.(ABSTRACT TRUNCATED AT 250 WORDS)